This project will examine multiple environmental agents and inherited traits in baboons for interactions with one another and for their effects on cholesterol induced atherosclerosis. The experimental period will extend from birth to sexual maturity. The initial experiment will determine the effects of infant nutrition (breast vs. formula) on serum lipids, cholesterol metabolism, hemostatic mechanisms, and the long term reaction of the animal to dietary cholesterol and type of fat. During the experimental period, measurements will include cholesterol absorption and turnover, coagulation factors and platelet functions, and fibrinogen and platelet turnover. Behavioural characteristics will be assessed by the signal count technique, and physical activity will be computed from activity records. The resulting data on each animal will be analyzed for effects of age, sex, infant diet, dietary cholesterol, type of dietary fat, behaviour, and physical activity on serum lipids and on atherosclerosis. In a second phase, the heritability of selected characteristics will be computed and selective matings will be designed to test heritability and to enhance and reduce heritable characteristics (such as response to cholesterol challenge) that are thought to be associated with atherosclerosis. Through observations on the baboons similar to those in the initial phase, the mechanism by which the inherited trait produces its effect on atherosclerosis will be examined.